The project involves genetic linkage of retinoschisis pedigrees, toward the end of positional cloning of the gene responsible for this human disease. Retinoschisis causes impaired central and peripheral vision and is a leading cause of juvenile macular degeneration. Thus far, the work has narrowed the genetic interval for the RS locus, from a previous 10 cM, to 3.4 cM, and now to 0.9 cM. This region is contained in 3 YACs, and we are searching for expressed sequences as candidate genes for retinoschisis.